Cis Azure Compute 2.3.12

Ensure managed identities are configured

Description

Managed identities from Microsoft Entra ID allow function apps to securely access other Azure services without the need to provision or rotate any secrets.

Rationale

Using managed identities with function apps eliminates the need to store and manage credentials to access Azure resources.

Impact

Minor administrative overhead to configure and manage role assignments for managed identities.

Audit Procedure

Using Azure Portal

1. Go to App Services or Function App.
2. Click the name of a function app.
3. Under Settings, click Identity.
4. Ensure that in the System assigned pane, the Status is set to On, and an Object (principal) ID is displayed, or that in the User assigned pane, a managed identity is listed.
5. Repeat steps 1-4 for each function app.

Using Azure CLI

Run the following command to list function apps:

az functionapp list

For each function app, run the following command to get the identity setting:

az functionapp show --resource-group <resource-group-name> --name <function-app-name> --query "identity"

Ensure that type is set to SystemAssigned, UserAssigned, or both.

Expected Result

The identity type should be set to SystemAssigned, UserAssigned, or both.

Remediation

Using Azure Portal

1. Go to App Services or Function App.
2. Click the name of a function app.
3. Under Settings, click Identity.
4. To add a system assigned managed identity:
   1. In the System assigned pane, under Status, click On.
   2. Click Save.
   3. Click Yes.
5. To add a user assigned managed identity:
   1. In the User assigned pane, click Add.
   2. Use the filter box to search for a managed identity.
   3. Select the identity.
   4. Click Add.
6. Repeat steps 1-5 for each function app requiring remediation.

Using Azure CLI

For each function app requiring remediation, run the following command to assign a system-assigned managed identity:

az functionapp identity assign --resource-group <resource-group-name> --name <function-app-name>

Using Azure PowerShell

For each function app requiring remediation, run the following command to assign a system-assigned managed identity:

Update-AzFunctionApp -ResourceGroupName <resource-group-name> -Name <function-app-name> -IdentityType SystemAssigned -Force

Default Value

Managed identities are disabled by default for function apps.

References

1. https://learn.microsoft.com/en-us/security/benchmark/azure/mcsb-identity-management#im-1-use-centralized-identity-and-authentication-system
2. https://learn.microsoft.com/en-us/azure/app-service/overview-managed-identity
3. https://learn.microsoft.com/en-us/cli/azure/functionapp
4. https://learn.microsoft.com/en-us/powershell/module/az.functions/update-azfunctionapp

Profile

Level 1 | Automated